The application of a viscous medium to a substrate, especially to a fabric web, poses a number of problems which have been difficult to solve heretofore. For example, fabric webs upon manufacture may have considerable widths, e.g. of 5 meters and more, and must be treated at high velocities. Especially under these conditions and when comparatively small quantities of the treating medium are to be applied, difficulties are encountered in obtaining a uniform distribution of the medium upon the substrate.
The flowable media with which the invention is concerned primarily are fabric-treatment agents in a viscous liquid state and foams thereof, e.g. for dyeing and other fabric treatment purposes.
In recent years it has been found to be desirable to apply chemical treatment agents to fabrics in the form of a foam but the application of such foams creates additional problems since there is a tendency for the consistency and other characteristics of the foam to alter with time. It is important, therefore, in such fabric treatment systems to exert efforts to ensure that the consistency and characteristic of the foam which is to contact the fabric do not change with time.
Considerable efforts with only limited success have been directed, therefore, to ensuring that the foam is completely uniform during fabrication and transport to the application region, that aging is prevented and/or aged or altered foam is precluded from being applied to the fabric, and that the foam is uniformly applied to the fabric over the entire width of the web.